Disinfecting solutions for use with contact lenses are well known in the art and the use of such lenses involves a daily disinfecting treatment regimen. The two most common methods of contact lens disinfection, cleaning and storage are multi-purpose disinfecting solutions and hydrogen peroxide-based solutions. The multi-purpose disinfecting solutions contain preservatives but hydrogen peroxide-based systems contain no preservative after hydrogen peroxide is neutralized and converted to Oxygen and water. Hydrogen peroxide is an effective microbial disinfectant, destroying pathogens by oxidation. Hydrogen peroxide systems, particularly 3% hydrogen peroxide solutions, have increasingly become popular as the disinfectant of choice for all types of daily and extended wear hydrogel lenses. The primary reason for their popularity is the rapid kill of microbial contaminants and low-residual hydrogen peroxide following the cleaning and disinfection regimen time. During hydrogen peroxide disinfection of lenses the natural and innocuous by products, O2 and water, are generated. See Krezanoski et al., “Journal of the American Optometric Association”, Vol. 59, Number 3, pages 193 197 (1988). In general, the hydrogen peroxide systems involve a hydrogen peroxide-containing disinfecting solution into which the contact lenses to be disinfected are placed and allowed to remain for a required period of time. The hydrogen peroxide may (1) oxidize chloride in the bacteria to hypochlorite or (2) decompose into nascent oxygen and hydroxyl radicals, thus providing a germicidal effect. Following the requisite time period a purposeful inactivation of the hydrogen peroxide is conducted, for example, with a platinum catalyst. Following inactivation, the contact lens may be safely re-inserted into the eye.
Contact lenses may be broadly divided into two categories: rigid gas permeable lenses, and soft, hydrogel lenses, although hybrids and other types of lenses exist. Soft or hydrogel lenses have become popular partly because they are comfortable to wear and require a shorter period of adaptation. Hydrogels are water swollen three-dimensional polymeric networks that are used in a variety of biomedical applications including drug delivery agents, prosthetic devices and contact lenses. The surface characteristics of hydrogels are partly determined by the orientation of hydrophobic and hydrophilic moieties of the macromolecules. See, e.g., Ketelson et al., Colloids and Surfaces B: Biointerfaces. Vol. 40. pages 1-9 (2005).
Because contact lenses are in intimate contact with the corneal surface and the human tear film, which is composed mainly of proteins, lipids, ions and mucins, the biocompatibility characteristics of the lenses are directly affected by the surface wettability properties of the hydrogel materials. In particular, evaluating the surface wettability properties of a lens material is important because such properties may affect the lens insertion and daily comfort. To maintain a stable tear film, a contact lens material must have hydrophilic surface properties. If the contact lens material exhibits mostly hydrophobic properties on the lens surface, the tear film may be disrupted. To determine the wettability of a surface via an aqueous solution, such as human lacrimal fluid, i.e., tears, the contact angle is measured. The spread of an aqueous fluid on a surface indicates that the surface exhibits a degree of hydrophilicity, thereby resulting in a low contact angle. The surface is hydrophobic if a drop of aqueous fluid does not spread, thereby resulting in a high contact angle. A new family of contact lens materials, silicone hydrogels, is replacing traditional hydrogels as the material of choice for extended wear soft contact lenses. Silicone hydrogel materials have significantly higher oxygen permeability than traditional soft lens hydrogels due to the presence of silicone functional groups. Additionally, the presence of silicone groups in silicone hydrogel materials results in a lens surface having hydrophobic properties.
Various techniques, for example, plasma surface treatments and incorporation of wetting agents within the lens material, have been utilized in order to provide a biocompatible, hydrophilic and wettable lens surface. An example of a silicone hydrogel lens with surface treatment is the AIR OPTIX™ contact lenses marketed by Alcon. These lenses are plasma coated. Although modifying the surface can improve biocompatibility, it has also been reported that some silicone hydrogel materials accumulate lipids over time, and that this build-up may result in a decrease in the wettability of the silicone hydrogel lens material and surface.
The wettability characteristics of the surfaces of contact lenses may also be modified by reducing the amount of hydrophobization on the surfaces. Surfactants have been utilized in prior compositions for treating contact lenses, for example, poloxamers and poloxamines, such as the Pluronic® and Tetronic® brands of surfactants, which are poly(oxyethylene)-poly(oxypropylene) (“PEO-PPO”) block copolymers, have been used extensively in prior products utilized to treat contact lenses. However, U.S. Patent application Publication No. 2011/0300019 (Ketelson et al.) discloses that such surfactants do not wet silicone hydrogel lenses efficiently.
U.S. Pat. No. 5,523,012 to Winterton, et al. teaches that the addition of a surface-active agent to a peroxide disinfection solution will enhance the disinfecting properties of the solution. However, the surfactants disclosed are all present in amounts above 0.1% and, because of excessive foaming, are incompatible with the platinum catalyst disc typically used to deactivate hydrogen peroxide in the lens disinfection systems.
U.S. Pat. No. 5,423,012 to Winterton discloses buffered peroxide formulations with poloxamine or poloxamer surface active agents.
U.S. Pat. No. 5,746,972 to Park, et al. teaches compositions and methods for disinfecting and cleaning contact lenses include a liquid medium containing hydrogen peroxide and a solid ethylene oxide/propylene oxide block copolymer surfactant having at least 70% by weight polyethylene oxide. The hydrogen peroxide is degraded by a catalase released into the solution and causes “a reduced amount of foam.” However, such compositions cause excessive foaming when a platinum catalyst is used to decompose the hydrogen peroxide.
A new class of surface-active agents has been found to efficiently wet silicone hydrogel lenses, namely, EO-BO copolymers. However, it has been found that EO-BO copolymers may cause excessive foaming when used in peroxide-based disinfecting solutions during neutralization, for example, with platinum catalyst discs.
U.S. Patent Application Publication No. 2008/0138310 (Ketelson et al.) is discloses the use of poly(oxyethylene)-poly(oxybutylene) block copolymers in pharmaceutical compositions.
In view of the foregoing, there is a need for new methods and compositions for improving the wettability of silicone hydrogel contact lenses as well as older lens types while minimizing foaming of peroxide-based contact lens disinfection formulations.